Effect of material deterioration on slab ballastless track performance under frost heaving and freezing-thawing

Taking the slab ballastless track in the frost heaving area of the Harbin-Dalian High-Speed Railway subgrade as the research object, the deterioration laws of materials properties under freezing-thawing cycles were investigated through the axial compression and splitting tensile failure tests on the standard cubic specimens of C60, C40 concrete and mortar under rapid freezing-thawing cycles. On this basis, a spatial finite element model was established for a CRTS Ⅰ slab ballastless track-subgrade frost heaving and freezing-thawing, considering the limit retaining boss, ring-shaped resin and interlayer bonding contact properties. The static properties of tracks after the freezing-thawing damage were studied, and the stress states and damage characteristics of the base plate were revealed. Research results demonstrate that the use of high strength grade concrete considerably decelerates the material deterioration and erosion due to the freezing-thawing cycle. Intense freezing-thawing cycles remarkably deteriorate the contact state of the structural interface. As the number of freezing-thawing cycle increases, the materials properties of mortar layer and base plate worsen significantly, their elastic moduli, interlayer bonding strengths, and axial tensile strengths decrease substantially. The peak compressive strengths of C60, C40 concrete and mortar decrease by 14.7%, 34.6%, and 29.9%, respectively, after 300 freezing-thawing cycles compared to those without any freezing-thawing cycles. The axial tensile strength of cementation interface between the C60 concrete and the mortar decreases by 90.6%. The axial tensile strengths of C60, C40 concrete and mortar decrease by more than 56%. Under the typical frost heaving condition (the frost heaving wave length is 10 m, and the frost heaving peak is 8 mm), the maximum tensile stress is observed at the upper surfaces of all structural layers of the track at the frost heaving center, whereas the maximum compressive stress is observed at the foot of the frost heaving wave. As the number of freezing-thawing cycle increases, the maximum tensile stresses of track slab and base plate also increase. Hence, when designing slab ballastless tracks in cold areas, the base plate is the main control component, and the frost heaving in the middle of the base plate is a highly unfavorable condition. 6 tabs, 11 figs, 32 refs.